1231135521 has 64 divisors (see below), whose sum is σ = 2174791680. Its totient is φ = 600687360.

The previous prime is 1231135517. The next prime is 1231135547. The reversal of 1231135521 is 1255311321.

It is not a de Polignac number, because 1231135521 - 2² = 1231135517 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1231135491 and 1231135500.

It is not an unprimeable number, because it can be changed into a prime (1231135621) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 245380 + ... + 250346.

It is an arithmetic number, because the mean of its divisors is an integer number (33981120).

Almost surely, 2^1231135521 is an apocalyptic number.

1231135521 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1231135521 is a deficient number, since it is larger than the sum of its proper divisors (943656159).

1231135521 is a wasteful number, since it uses less digits than its factorization.

1231135521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5054.

The product of its digits is 900, while the sum is 24.

The square root of 1231135521 is about 35087.5408229189. The cubic root of 1231135521 is about 1071.7708821181.

Adding to 1231135521 its reverse (1255311321), we get a palindrome (2486446842).

The spelling of 1231135521 in words is "one billion, two hundred thirty-one million, one hundred thirty-five thousand, five hundred twenty-one".